No vacuum advance when hooked to carb? - Team Camaro Tech
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post #1 of 7 (permalink) Old Feb 21st, 06, 05:15 PM Thread Starter
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No vacuum advance when hooked to carb?

When I am plugged into the carb with the vacuum advance from the distributor, nothing happens and I run 10 on the vacuum gauge. When I put the vacuum advance from the distributor into an intake port, I get the correct 20 reading and the vacuum gauge and the vacuum advance kicks in. Whats the deal? Can I just plug the carb port and continue to run it into the intake?
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post #2 of 7 (permalink) Old Feb 21st, 06, 05:21 PM
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Re: No vacuum advance when hooked to carb?

Quote:
Originally Posted by wheezer
Can I just plug the carb port and continue to run it into the intake?
Yes you can.
There are usually more than one port on the carb. Some, like the one you pluged into, are "ported vacaum" and only have vacaum above idle. If you see one that is "lower" that will probably work, but plugging it into the manifold is fine too.





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post #3 of 7 (permalink) Old Feb 21st, 06, 05:59 PM
 
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Re: No vacuum advance when hooked to carb?

usually on the carbs vac port theres no vac present at idle, only as rpm increases and theres need for additional advance at idle.only under additional load.its normal to have no advance at idle.with it disconnected from the correct port on your carb, rev it to say 2500 hold it and connect the vac line to the ported vac source on your carb and your rpm should increase.hooking it to a intake vac port will increase your initial timing from 12-14 degrees or what ever your running to full advance 26-34degrees, thats fine long as you compensate by reducing your timing.try testing your present setup with a advance timing light,im quite sure its advancing.on a holley its the port on the left side behind the front bowl on the metering block.
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post #4 of 7 (permalink) Old Feb 21st, 06, 06:47 PM
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Re: No vacuum advance when hooked to carb?

Quote:
Originally Posted by wheezer
When I am plugged into the carb with the vacuum advance from the distributor, nothing happens and I run 10 on the vacuum gauge. When I put the vacuum advance from the distributor into an intake port, I get the correct 20 reading and the vacuum gauge and the vacuum advance kicks in. Whats the deal? Can I just plug the carb port and continue to run it into the intake?
Is this a stock motor?
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post #5 of 7 (permalink) Old Feb 21st, 06, 06:54 PM Thread Starter
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Re: No vacuum advance when hooked to carb?

350 HO crate. Stupid question...what does the vacuum line going to the canister in the driver side quarter do? The other end from the canister goes through the fire wall. Does this possibly have to do with my defunct AC? I have manual brakes.
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post #6 of 7 (permalink) Old Feb 23rd, 06, 01:44 PM
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Re: No vacuum advance when hooked to carb?

Quote:
Originally Posted by 1979schugger
hooking it to a intake vac port will increase your initial timing from 12-14 degrees or what ever your running to full advance 26-34degrees, thats fine long as you compensate by reducing your timing.
There's no need to to reduce your timing when changing from "ported" vacuum to full manifold vacuum, as total timing (initial plus centrifugal) isn't related to the vacuum advance at all; manifold-connected vacuum advance will add about 15* to idle timing (assuming you have the correct advance can), which will improve idle stability, idle cooling, and throttle response. You will, however, have to re-adjust idle speed and idle mixture, as idle speed will increase with the added idle advance.

JohnZ
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post #7 of 7 (permalink) Old Feb 24th, 06, 05:02 AM Thread Starter
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Re: No vacuum advance when hooked to carb?

thanks. seems to respond much better with intake vacuum. no hestitation when goosed.
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